CMOS image sensor structure with crosstalk improvement

ABSTRACT

A semiconductor device includes a substrate, a semiconductor layer, light-sensing devices, a transparent dielectric layer and a grid shielding layer. The semiconductor layer overlies the substrate, and has a first surface and a second surface opposite to the first surface. The semiconductor layer includes microstructures disposed on the second surface of the semiconductor layer. The light-sensing devices are disposed on the first surface of the semiconductor layer. The transparent dielectric layer is disposed on the second surface of the semiconductor layer, and covers the microstructures. The grid shielding layer extends from the first surface of the semiconductor layer toward the second surface of the semiconductor layer, and surrounds each of the light-sensing devices to separate the light-sensing devices from each other, in which a depth of the grid shielding layer is greater than two-thirds of a thickness of the semiconductor layer.

BACKGROUND

Semiconductor image sensors are operated to sense light. Typically, thesemiconductor image sensors include complementarymetal-oxide-semiconductor (CMOS) image sensors (CIS) and charge-coupleddevice (CCD) sensors, which are widely used in various applications suchas digital still camera (DSC), mobile phone camera, digital video (DV)and digital video recorder (DVR) applications. These semiconductor imagesensors utilize an array of image sensor elements, each image sensorelement including a photodiode and other elements, to absorb light andconvert the sensed light into digital data or electrical signals.

Front side illuminated (FSI) CMOS image sensors and back sideilluminated (BSI) CMOS image sensors are two types of CMOS imagesensors. The FSI CMOS image sensors are operable to detect lightprojected from their front side while the BSI CMOS image sensors areoperable to detect light projected from their backside. When lightprojected into the FSI CMOS image sensors or the BSI CMOS image sensors,photoelectrons are generated and then are sensed by light-sensingdevices in pixels of the image sensors. The more the photoelectrons aregenerated, the more superior quantum efficiency (QE) the image sensorhas, thus improving the image quality of the CMOS image sensors.

However, while CMOS image sensor technologies are rapidly developed,CMOS image sensors with higher quantum efficiency are desired.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1A is a schematic cross-sectional view of a semiconductor device inaccordance with various embodiments.

FIG. 1B is a schematic top view of a semiconductor device in accordancewith various embodiments.

FIG. 2A is a schematic cross-sectional view of a semiconductor device inaccordance with various embodiments.

FIG. 2B is a schematic top view of a semiconductor device in accordancewith various embodiments.

FIG. 3A through FIG. 3G are schematic cross-sectional views ofintermediate stages showing a method for manufacturing a semiconductordevice in accordance with various embodiments.

FIG. 4 is a flow chart of a method for manufacturing a semiconductordevice in accordance with various embodiments.

FIG. 5A through FIG. 5G are schematic cross-sectional views ofintermediate stages showing a method for manufacturing a semiconductordevice in accordance with various embodiments.

FIG. 6 is a flow chart of a method for manufacturing a semiconductordevice in accordance with various embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact.

Terms used herein are only used to describe the specific embodiments,which are not used to limit the claims appended herewith. For example,unless limited otherwise, the term “one” or “the” of the single form mayalso represent the plural form. The terms such as “first” and “second”are used for describing various devices, areas and layers, etc., thoughsuch terms are only used for distinguishing one device, one area or onelayer from another device, another area or another layer. Therefore, thefirst area can also be referred to as the second area without departingfrom the spirit of the claimed subject matter, and the others arededuced by analogy. In addition, the present disclosure may repeatreference numerals and/or letters in the various examples. Thisrepetition is for the purpose of simplicity and clarity and does not initself dictate a relationship between the various embodiments and/orconfigurations discussed. As used herein, the term “and/or” includes anyand all combinations of one or more of the associated listed items.

In a typical CMOS image sensor, various microstructures are formed on asurface of a semiconductor layer, and are closely adjacent to atransparent dielectric layer for increasing light absorption of thesemiconductor layer, thus increasing photoelectrons generated in thesemiconductor layer via multiple reflections and/or refractions oflight. Accordingly, a quantum efficiency of the CMOS image sensor isincreased. However, the light and the photoelectrons may be diffused toadjoining pixels due to the multiple reflections and/or the refractionsof the light, thereby increasing crosstalk effects of the CMOS imagesensor.

Embodiments of the present disclosure are directed to providing asemiconductor device and a method for manufacturing the semiconductordevice, in which a grid shielding layer is disposed in a semiconductorlayer to define the semiconductor layer into various pixel regions andto separate the pixel regions from each other, so that photoelectronsand reflected light and/or refracted light from the semiconductor layercan be blocked within any one of the pixel regions by the grid shieldinglayer. Accordingly, a crosstalk effect of the semiconductor device canbe significantly improved.

FIG. 1A is schematic cross-sectional view of a semiconductor device inaccordance with various embodiments. In some embodiments, asemiconductor device 100 is a CMOS image sensor device, which may beoperated for sensing incident light 102. The semiconductor device 100has a front side 104 and a back side 106. In some embodiments, thesemiconductor device 100 is a FSI CMOS image sensor device, which isoperated to sense the incident light 102 projected from its front side104. As shown in FIG. 1A, the semiconductor device 100 includes asubstrate 108, a transparent dielectric layer 110, a semiconductor layer112, various light-sensing devices 114 and a grid shielding layer 116.The substrate 108 is a semiconductor substrate. The substrate 108 iscomposed of a single-crystalline semiconductor material or a compoundsemiconductor material. For example, the substrate 108 is a siliconsubstrate. In some examples, germanium or glass may also be used as amaterial of the substrate 108.

The semiconductor layer 112 is disposed over the substrate 108. In someexamples, the semiconductor layer 112 is formed from epitaxial siliconand/or epitaxial germanium. The semiconductor layer 112 has a firstsurface 120 and a second surface 122, which are located on two oppositesides of the semiconductor layer 112. In some examples, a thickness ofthe semiconductor layer 112 ranges from 0.1 micrometers to 20micrometers. The semiconductor layer 112 includes variousmicrostructures 124 formed on the second surface 122. In some examples,each microstructure 124 has a cross-section in a shape of triangle,trapezoid or arc such as semi-circle or semi-ellipse. Themicrostructures 124 may be periodically arranged or unperiodicallyarranged. In addition, any two adjacent microstructures 124 may adjointo each other, or may be separated from each other.

The transparent dielectric layer 110 is disposed on the second surface122 of the semiconductor layer 112 and covers the microstructures 124.In some embodiments, as shown in FIG. 1A, the transparent dielectriclayer 110 is located on a surface 118 of the substrate 108 and betweenthe substrate 108 and the semiconductor layer 112. In some examples, arefractive index of the semiconductor layer 112 is greater than that ofthe transparent dielectric layer 110. For example, the transparentdielectric layer 110 is formed from silicon dioxide, silicon nitride orsilicon oxynitride while the semiconductor layer 112 is formed fromepitaxial silicon.

By forming the microstructures 124 on the second surface 122 of thesemiconductor layer 112 and forming the transparent dielectric layer 110with a refractive index smaller than that of the semiconductor layer112, a total reflection angle of the incident light 102 emitted from thesemiconductor layer 112 to the transparent dielectric layer 110 isrelatively small, so that some of the incident light 102 can bereflected back to the semiconductor layer 112, thereby increasing anamount of photoelectrons generated by the semiconductor layer 112.Hence, a quantum efficiency of the semiconductor device 100 isincreased.

Simultaneously referring to FIG. 1A and FIG. 1B, FIG. 1B is a schematictop view of a semiconductor device in accordance with variousembodiments. As shown in FIG. 1A, the grid shielding layer 116 isdisposed in the semiconductor layer 112 and extends from the firstsurface 120 toward the second surface 122 of the semiconductor layer112. As shown in FIG. 1B, the grid shielding layer 116 defines thesemiconductor layer 112 into various pixel regions 126, and surroundseach of the pixel regions 126 to separate the pixel regions 126 fromeach other. In some examples, a depth of the grid shielding layer 116 isgreater than two-thirds of the thickness of the semiconductor layer 112.In certain examples, the grid shielding layer 116 penetrates through thesemiconductor layer 112, i.e. the grid shielding layer 116 extends fromthe first surface 120 to the second surface 122 of the semiconductorlayer 112, and the depth of the grid shielding layer 116 is equal to thethickness of the semiconductor layer 112. In some examples, the gridshielding layer 116 is formed from an electrically insulating material.In addition, a refractive index of the semiconductor layer 112 isgreater than that of the grid shielding layer 116. For example, the gridshielding layer 116 is formed from silicon dioxide, silicon nitride orsilicon oxynitride while the semiconductor layer 112 is formed fromepitaxial silicon.

By forming the grid shielding layer 116 with a refractive index smallerthan that of the semiconductor layer 112, a total reflection angle ofthe incident light 102 projected from the semiconductor layer 112 to thegrid shielding layer 116 is relatively small, so that most of theincident light 102 can be reflected back to the semiconductor layer 112,thereby increasing an amount of photoelectrons generated by thesemiconductor layer 112 and significantly blocking the incident light102 reflected and/or refracted by any one of the pixel regions fromentering the adjoining pixel regions 126. Hence, a quantum efficiency ofthe semiconductor device 100 is increased and a crosstalk effect of thesemiconductor device 100 is improved. Moreover, by forming the gridshielding layer 116 from an electrically insulating material,photoelectrons generated in any one of the pixel regions 126 can beblocked by the grid shielding layer 116 from entering the adjoiningpixel regions 126. Accordingly, the crosstalk effect of thesemiconductor device 100 can be further improved.

The light-sensing devices 114 are operated to sense the incident light102. Referring to FIG. 1A again, the light-sensing devices 114 aredisposed on the first surface 120 of the semiconductor layer 112 and arerespectively located in the pixel regions 126. Hence, the grid shieldinglayer 116 surrounds each of the light-sensing devices 114 respectivelylocated in the pixel regions 126, so as to separate the light-sensingdevices 114 from each other. In some examples, each light-sensing device114 includes an image sensor element, in which the image sensor elementincludes a photodiode and other elements.

In some examples, the semiconductor device 100 may optionally include apassivation layer 128 disposed on the first surface 120 of thesemiconductor layer 112, the passivation layer 128 covering thelight-sensing devices 114, the grid shielding layer 116 and the firstsurface 120 of the semiconductor layer 112. The passivation layer 128 issuitable for use in protecting the light-sensing devices 114, the gridshielding layer 116 and the semiconductor layer 112 from being damaged.The passivation layer 128 may be formed from silicon oxide, siliconnitride or silicon oxynitride.

FIG. 2A is schematic cross-sectional view of a semiconductor device inaccordance with various embodiments. In some embodiments, asemiconductor device 200 is a CMOS image sensor device, which may beoperated for sensing incident light 202. The semiconductor device 200has a front side 204 and a back side 206. In some embodiments, thesemiconductor device 200 is a BSI CMOS image sensor device, which isoperated to sense the incident light 202 projected from its back side206. As shown in FIG. 2A, the semiconductor device 200 includes asubstrate 208, a semiconductor layer 212, a transparent dielectric layer210, various light-sensing devices 214 and a grid shielding layer 216.The substrate 208 is a semiconductor substrate. The substrate 208 iscomposed of a single-crystalline semiconductor material or a compoundsemiconductor material. In some examples, the substrate 208 is a siliconsubstrate. In some embodiments, germanium or glass may also be used as amaterial of the substrate 208.

The semiconductor layer 212 is disposed over a surface 218 of thesubstrate 208. In some examples, the semiconductor layer 212 is formedfrom epitaxial silicon and/or epitaxial germanium. The semiconductorlayer 212 has a first surface 220 and a second surface 222 opposite tothe first surface 220. In some examples, a thickness of thesemiconductor layer 212 ranges from 0.1 micrometers to 20 micrometers.The semiconductor layer 212 includes various microstructures 224 formedon the second surface 222. In some examples, each microstructure 224 hasa cross-section in a shape of triangle, trapezoid or arc such assemi-circle or semi-ellipse. The microstructures 224 may be periodicallyarranged or unperiodically arranged. In addition, any two adjacentmicrostructures 224 may adjoin to each other, or may be separated fromeach other.

The transparent dielectric layer 210 is disposed on the second surface222 of the semiconductor layer 212 and covers the microstructures 224.In some embodiments, as shown in FIG. 2A, the semiconductor layer 212 islocated between the substrate 208 and the transparent dielectric layer210. In some examples, a refractive index of the semiconductor layer 212is greater than that of the transparent dielectric layer 210. In someexemplary examples, the transparent dielectric layer 210 is formed fromsilicon dioxide, silicon nitride or silicon oxynitride while thesemiconductor layer 212 is formed from epitaxial silicon.

With the microstructures 224 formed on the second surface 222 of thesemiconductor layer 212 and the transparent dielectric layer 210 with arefractive index smaller than that of the semiconductor layer 212covering the microstructures 224 of the semiconductor layer 212, an areaof the second surface 222 is increased, and an incident angle of theincident light 202 projected to the second surface 222 is smaller thanthat of the incident light 222 projected to a planar surface, so thatmost of the incident light 202 can be multiply refracted and reflectedin the microstructures 224, thereby increasing an amount ofphotoelectrons generated by the semiconductor layer 212. Hence, aquantum efficiency of the semiconductor device 200 is increased.

Simultaneously referring to FIG. 2A and FIG. 2B, FIG. 2B is a schematictop view of a semiconductor device in accordance with variousembodiments. As shown in FIG. 2A, the grid shielding layer 216 isdisposed in the semiconductor layer 212 and extends from the firstsurface 220 toward the second surface 222 of the semiconductor layer212. As shown in FIG. 2A and FIG. 2B, the grid shielding layer 216defines the semiconductor layer 212 into various pixel regions 226, andsurrounds each of the pixel regions 226 to separate the pixel regions226 from each other. In some examples, a depth of the grid shieldinglayer 216 is greater than two-thirds of the thickness of thesemiconductor layer 212. In certain examples, the grid shielding layer216 penetrates through the semiconductor layer 212, i.e. the gridshielding layer 216 extends from the first surface 220 to the secondsurface 222 of the semiconductor layer 212, and the depth of the gridshielding layer 216 is equal to the thickness of the semiconductor layer212. In some examples, the grid shielding layer 216 is formed from anelectrically insulating material. In addition, a refractive index of thegrid shielding layer 216 is smaller than that of the semiconductor layer212. In some exemplary examples, the grid shielding layer 216 is formedfrom silicon dioxide, silicon nitride or silicon oxynitride while thesemiconductor layer 212 is formed from epitaxial silicon.

By forming the grid shielding layer 216 with a refractive index smallerthan that of the semiconductor layer 212, a total reflection angle ofthe incident light 202 from the semiconductor layer 212 to the gridshielding layer 216 is relatively small, so that most of the incidentlight 202 can be reflected back to the semiconductor layer 212, therebysignificantly blocking the incident light 202 reflected and/or refractedby any one of the pixel regions from entering the adjoining pixelregions 226, thus increasing an amount of photoelectrons generated bythe semiconductor layer 212. Therefore, a crosstalk effect of thesemiconductor device 200 is improved and a quantum efficiency of thesemiconductor device 200 is increased. Furthermore, by forming the gridshielding layer 216 from an electrically insulating material,photoelectrons generated in any one of the pixel regions 226 can beblocked by the grid shielding layer 216 from diffusing to the adjoiningpixel regions 226. Accordingly, the crosstalk effect of thesemiconductor device 200 can be further improved.

The light-sensing devices 214 are operated to sense the incident light202. Referring to FIG. 2A again, the light-sensing devices 214 aredisposed on the first surface 220 of the semiconductor layer 212 andrespectively located in the pixel regions 226. Thus, the grid shieldinglayer 216 surrounds each of the light-sensing devices 214 respectivelylocated in the pixel regions 226, so as to separate the light-sensingdevices 214 from each other. In some examples, each light-sensing device214 includes an image sensor element, in which the image sensor elementincludes a photodiode and other elements.

Referring to FIG. 2A again, in some examples, the semiconductor device200 may optionally include a passivation layer 232 disposed on thetransparent dielectric layer 210 and covering the microstructures 224,in which the passivation layer 232 and the semiconductor layer 212 aredisposed on opposite sides of the transparent dielectric layer 210. Thepassivation layer 232 is suitable for protecting the transparentdielectric layer 210 and the microstructures 224 underlying thetransparent dielectric layer 210 from being damaged. The passivationlayer 232 may be formed from silicon oxide, silicon nitride or siliconoxynitride.

In some examples, as shown in FIG. 2A, the semiconductor device 200 mayoptionally include another passivation layer 228 disposed on the firstsurface 220 of the semiconductor layer 212, the passivation layer 228covering the light-sensing devices 214, the grid shielding layer 216 andthe first surface 220 of the semiconductor layer 212. The passivationlayer 228 is suitable for protecting the light-sensing devices 214, thegrid shielding layer 216 and the semiconductor layer 212 from beingdamaged. The passivation layer 228 may be formed from silicon oxide,silicon nitride or silicon oxynitride. Referring to FIG. 2A again, incertain examples, the semiconductor device 200 may optionally include abonding layer 230 disposed between the surface 218 of the substrate 208and the passivation layer 228 for bonding the substrate 208 to thepassivation layer 228. For example, the bonding layer 230 may be formedfrom silicon dioxide.

Referring to FIG. 3A through FIG. 3G, FIG. 3A through FIG. 3G areschematic cross-sectional views of intermediate stages showing a methodfor manufacturing a semiconductor device in accordance with variousembodiments. As shown in FIG. 3A, a substrate 300 is provided. Thesubstrate 300 is a semiconductor substrate and may be composed of asingle-crystalline semiconductor material or a compound semiconductormaterial. In some examples, silicon, germanium or glass may be used as amaterial of the substrate 300. A semiconductor layer 304 is formed on asurface 302 of the substrate 300 by using, for example, a depositiontechnique or an epitaxial technique. In some examples, the operation ofproviding the substrate 300 includes forming the semiconductor layer 304from epitaxial silicon and/or epitaxial germanium. The semiconductorlayer 304 has a first surface 306 and a second surface 308 opposite tothe first surface 306. In some examples, a thickness of thesemiconductor layer 304 ranges from 0.1 micrometers to 20 micrometers.

As shown in FIG. 3B and FIG. 3C, various microstructures 314 are formedon the second surface 308 of the semiconductor layer 304. In someexamples, the operation of forming the microstructures 314 is performedusing a photolithography process and an etching process. Thephotolithography process is performed to define regions where themicrostructures 314 are formed, and the etching process is performed onthe second surface 308 to remove a portion of the semiconductor layer304, so as to form the microstructures 314 on the second surface 308according to the definition of the photolithography process. In thephotolithography process, a mask layer 310 is formed on the secondsurface 308 of the semiconductor layer 304 by using, for example, a spincoating method. The mask layer 310 may be formed from a photo-resistmaterial. An exposure operation and a development operation aresubsequently performed on the mask layer 310 to pattern the mask layer310. As shown in FIG. 3B, after patterning, the mask layer 310 exposes aportion of the second surface 308 of the semiconductor layer 304. Anetching operation 312, such as a dry etching operation and a wet etchingoperation, is performed on the second surface 308 exposed by the masklayer 310 to form the microstructures 314 on the second surface 308 ofthe semiconductor layer 304, as shown in FIG. 3C. For example, theetching operation 312 is performed using plasma. The mask layer 310 isremoved from the second surface 310 after the etching operation 312 iscompleted. In some examples, each microstructure 314 is formed with across-section in a shape of triangle, trapezoid or arc such assemi-circle or semi-ellipse. The microstructures 314 may be formedperiodically or unperiodically. In addition, the operation of formingthe microstructures 314 may be performed to form any two adjacentmicrostructures 314 adjoining to each other or being separated from eachother.

As shown in FIG. 3C, a transparent dielectric layer 316 is formed on thesecond surface 308 of the semiconductor layer 304 and covering themicrostructures 314. In some examples, in the operation of forming thetransparent dielectric layer 316, the transparent dielectric layer 316is firstly formed to cover the microstructures 314, and then aplanarization operation is performed on the transparent dielectric layer314 to planarize a surface 318 of the transparent dielectric layer 316.Thus, the surface 318 of the transparent dielectric layer 316 is planarafter the planarization operation. In some exemplary examples, theoperation of forming the transparent dielectric layer 316 is performedusing a thermal oxidation technique or a chemical vapor deposition (CVD)technique. In addition, the planarization operation is performed using achemical mechanical polishing (CMP) technique. In some examples, theoperation of forming the transparent dielectric layer 316 includesforming the transparent dielectric layer 316 using a material having arefractive index which is smaller than a refractive index of thesemiconductor layer 304. For example, the operation of forming thetransparent dielectric layer 316 includes forming the transparentdielectric layer 316 from silicon dioxide, silicon nitride or siliconoxynitride while the operation of the semiconductor layer 304 includesforming the semiconductor layer 304 from epitaxial silicon.

As shown in FIG. 3D, another substrate 320 is provided and then isbonded to the surface 318 of the transparent dielectric layer 316.Because the surface 318 of the transparent dielectric layer 316 isplanarized, the substrate 320 can be successfully bonded to thetransparent dielectric layer 316. In some examples, the substrate 320 isa semiconductor substrate and may be composed of a single-crystallinesemiconductor material or a compound semiconductor material. In someexamples, silicon, germanium or glass may be used as a material of thesubstrate 320.

As shown in FIG. 3E, the structure composed of the substrate 300, thesemiconductor layer 304, the transparent dielectric layer 316 and thesubstrate 320 is reversed, and the substrate 300 is removed to exposethe first surface 306 of the semiconductor layer 304. In some examples,the operation of removing the substrate 300 is performed using athinning technique, such as a wet etching technique and a CMP technique.

As shown in FIG. 3F, a grid shielding layer 328 is formed in thesemiconductor layer 304 and extends from the first surface 306 towardthe second surface 308 of the semiconductor layer 304, so as to definethe semiconductor layer 304 into various pixel regions 326. The gridshielding layer 328 surrounds each of the pixel regions 326 to separatethe pixel regions 326 from each other. In some examples, a depth of thegrid shielding layer 328 is greater than two-thirds of the thickness ofthe semiconductor layer 304. In certain examples, the grid shieldinglayer 328 penetrates through the semiconductor layer 304, i.e. the gridshielding layer 328 extends from the first surface 306 to the secondsurface 308 of the semiconductor layer 304, and the depth of the gridshielding layer 328 is equal to the thickness of the semiconductor layer304. In some examples, in the operation of forming the grid shieldinglayer 328, a trench 324 is formed in the semiconductor layer 304 using,for example, a photolithography process and an etching process. Thetrench 324 is formed to extend from the first surface 306 toward thesecond surface 308, so as to form the pixel regions 326 in thesemiconductor layer 304. The operation of forming the trench 324includes forming the trench 324 surrounding each of the pixel regions326 and separating the pixel regions 326 from each other. In someexamples, after the trench 324 is formed, the grid shielding layer 328is formed to fill into the trench 324 by using a deposition technique,such as a CVD technique. A removal operation may be optionally performedto remove an excess portion of the grid shielding layer 328 on the firstsurface 306 of the semiconductor layer 304.

In some examples, the grid shielding layer 328 is formed from anelectrically insulating material. In addition, the operation of formingthe grid shielding layer 328 is performed to form the grid shieldinglayer 328 using a material having a refractive index which is smallerthan that of the semiconductor layer 304. In some exemplary examples,the grid shielding layer 328 is formed from silicon dioxide, siliconnitride or silicon oxynitride while the semiconductor layer 304 isformed from epitaxial silicon.

As shown in FIG. 3G, various light-sensing devices 330 are formed on thefirst surface 306 of the semiconductor layer 304 and are respectivelydisposed in the pixel regions 326 to complete a semiconductor device334. Thus, the grid shielding layer 328 separates the light-sensingdevices 330 from each other. In some examples, each light-sensing device330 includes an image sensor element, in which the image sensor elementincludes a photodiode and other elements.

In some examples, a passivation layer 332 may be optionally formed onthe first surface 306 of the semiconductor layer 304 and covering thelight-sensing devices 330, the grid shielding layer 328 and the firstsurface 306 of the semiconductor layer 304 for protecting thelight-sensing devices 330, the grid shielding layer 328 and thesemiconductor layer 304 from being damaged. The passivation layer 332may be formed from silicon oxide, silicon nitride or silicon oxynitride.

Referring to FIG. 4 with FIG. 3A through FIG. 3G, FIG. 4 is a flow chartof a method for manufacturing a semiconductor device in accordance withvarious embodiments. The method begins at operation 400, where asubstrate 300 is provided, and a semiconductor layer 304 is formed on asurface 302 of the substrate 300, as shown in FIG. 3A. The semiconductorlayer 304 may be formed using, for example, a deposition technique or anepitaxial technique. The semiconductor layer 304 has a first surface 306and a second surface 308 opposite to the first surface 306. In someexamples, a thickness of the semiconductor layer 304 ranges from 0.1micrometers to 20 micrometers.

At operation 402, as shown in FIG. 3B and FIG. 3C, variousmicrostructures 314 are formed on the second surface 308 of thesemiconductor layer 304 using, for example, a photolithography processand an etching process. In some examples, in the photolithographyprocess, a mask layer 310 is formed on the second surface 308 of thesemiconductor layer 304 by using a spin coating method. An exposureoperation and a development operation are subsequently performed on themask layer 310 to pattern the mask layer 310, as shown in FIG. 3B. Anetching operation 312, such as a dry etching operation and a chemicaletching operation, is performed on the second surface 308 exposed by themask layer 310 to form the microstructures 314 on the second surface308, as shown in FIG. 3C. The etching operation 312 may be performedusing plasma. The operation of forming the microstructures 314 may beperformed to form each microstructure 314 with a cross-section in ashape of triangle, trapezoid or arc such as semi-circle or semi-ellipse.The microstructures 314 may be formed periodically or unperiodically. Inaddition, the operation of forming the microstructures 314 may beperformed to form any two adjacent microstructures 314 adjoining to eachother or being separated from each other.

At operation 404, referring to FIG. 3C again, a transparent dielectriclayer 316 is formed on the second surface 308 of the semiconductor layer304 and covering the microstructures 314 using, for example, a thermaloxidation technique or a CVD technique. In some examples, aplanarization operation may be optionally performed on the transparentdielectric layer 314 to planarize a surface 318 of the transparentdielectric layer 316. For example, the planarization operation isperformed using a CMP technique. The operation of forming thetransparent dielectric layer 316 includes forming the transparentdielectric layer 316 using a material having a refractive index which issmaller than a refractive index of the semiconductor layer 304. In someexemplary examples, the operation of forming the transparent dielectriclayer 316 includes forming the transparent dielectric layer 316 fromsilicon dioxide, silicon nitride or silicon oxynitride.

At operation 406, as shown in FIG. 3D, another substrate 320 is providedand bonded to the surface 318 of the transparent dielectric layer 316.At operation 408, as shown in FIG. 3E, the structure composed of thesubstrate 300, the semiconductor layer 304, the transparent dielectriclayer 316 and the substrate 320 is reversed, and the substrate 300 isremoved to expose the first surface 306 of the semiconductor layer 304using, for example, a thinning technique. In some examples, theoperation of removing the substrate 300 is performed using a wet etchingtechnique and a CMP technique.

At operation 410, as shown in FIG. 3F, a grid shielding layer 328 isformed in the semiconductor layer 304. In the operation of forming thegrid shielding layer 328, a trench 324 is formed in the semiconductorlayer 304 using, for example, a photolithography process and an etchingprocess. The trench 324 is formed to extend from the first surface 306toward the second surface 308 of the semiconductor layer 304, so as todefine pixel regions 326 in the semiconductor layer 304. The operationof forming the trench 324 includes forming the trench 324 surroundingeach of the pixel regions 326 and separating the pixel regions 326 fromeach other. Then, the grid shielding layer 328 is formed to fill intothe trench 324 by using a deposition technique, such as a CVD technique.The trench 324 surrounds each of the pixel regions 326 and separates thepixel regions 326 from each other, so that the grid shielding layer 328filling the trench 324 extends from the first surface 306 toward thesecond surface 308 and surrounds each of the pixel regions 326 toseparate the pixel regions 326 from each other. In some examples, adepth of the grid shielding layer 328 is greater than two-thirds of thethickness of the semiconductor layer 304. In certain examples, the gridshielding layer 328 penetrates through the semiconductor layer 304, andthe depth of the grid shielding layer 328 is equal to the thickness ofthe semiconductor layer 304. In some examples, a removal operation maybe optionally performed to remove an excess portion of the gridshielding layer 328 on the first surface 306 of the semiconductor layer304.

In some examples, the grid shielding layer 328 is formed from anelectrically insulating material. In some exemplary examples, the gridshielding layer 328 is formed using a material having a refractive indexwhich is smaller than that of the semiconductor layer 304. For example,the grid shielding layer 328 is formed from silicon dioxide, siliconnitride or silicon oxynitride.

At operation 412, as shown in FIG. 3G, various light-sensing devices 330are formed on the first surface 306 of the semiconductor layer 304 andare respectively disposed in the pixel regions 326 to complete asemiconductor device 334. The grid shielding layer 328 separates thepixel regions 326, so that the grid shielding layer 328 separates thelight-sensing devices 330 respectively in the pixel regions 326 fromeach other. In some examples, each light-sensing device 330 includes animage sensor element, in which the image sensor element includes aphotodiode and other elements. Optionally, a passivation layer 332 maybe formed on the first surface 306 of the semiconductor layer 304 andcovering the light-sensing devices 330, the grid shielding layer 328 andthe first surface 306 of the semiconductor layer 304 for protecting.

Referring to FIG. 5A through FIG. 5G, FIG. 5A through FIG. 5G areschematic cross-sectional views of intermediate stages showing a methodfor manufacturing a semiconductor device in accordance with variousembodiments. As shown in FIG. 5A, a substrate 500 is provided. Thesubstrate 500 is a semiconductor substrate and may be composed of asingle-crystalline semiconductor material or a compound semiconductormaterial. In some examples, silicon, germanium or glass may be used as amaterial of the substrate 500. A semiconductor layer 504 is formed on asurface 502 of the substrate 500 by using, for example, a depositiontechnique or an epitaxial technique. In some examples, the operation ofproviding the substrate 500 includes forming the semiconductor layer 504from epitaxial silicon and/or epitaxial germanium. The semiconductorlayer 504 has a first surface 506 and a second surface 508 opposite toeach other. In some examples, a thickness of the semiconductor layer 504ranges from 0.1 micrometers to 20 micrometers.

As shown in FIG. 5B, a grid shielding layer 514 is formed in thesemiconductor layer 504 and extends from the first surface 506 towardthe second surface 508 of the semiconductor layer 504, so as to definethe semiconductor layer 504 into various pixel regions 512. The gridshielding layer 514 surrounds each of the pixel regions 512 to separatethe pixel regions 512 from each other. In some examples, a depth of thegrid shielding layer 514 is greater than two-thirds of the thickness ofthe semiconductor layer 504. In certain examples, the grid shieldinglayer 514 penetrates through the semiconductor layer 504, i.e. the gridshielding layer 514 extends from the first surface 506 to the secondsurface 508 of the semiconductor layer 504, and the depth of the gridshielding layer 514 is equal to the thickness of the semiconductor layer504. In some examples, in the operation of forming the grid shieldinglayer 514, a trench 510 is formed in the semiconductor layer 504 using,for example, a photolithography process and an etching process. Thetrench 510 is formed to extend from the first surface 506 toward thesecond surface 508, so as to form the pixel regions 512 in thesemiconductor layer 504. The operation of forming the trench 510includes forming the trench 510 surrounding each of the pixel regions512 and separating the pixel regions 512 from each other. In someexamples, after the trench 510 is formed, the grid shielding layer 514is formed to fill into the trench 510 by using a deposition technique,such as a CVD technique. A removal operation may be optionally performedto remove an excess portion of the grid shielding layer 514 on the firstsurface 506 of the semiconductor layer 504.

In some examples, the grid shielding layer 514 is formed from anelectrically insulating material. In addition, the operation of formingthe grid shielding layer 514 is performed to form the grid shieldinglayer 514 using a material having a refractive index which is smallerthan that of the semiconductor layer 504. In some exemplary examples,the grid shielding layer 514 is formed from silicon dioxide, siliconnitride or silicon oxynitride while the semiconductor layer 504 isformed from epitaxial silicon.

As shown in FIG. 5C, various light-sensing devices 516 are formed on thefirst surface 506 of the semiconductor layer 504 and are respectivelydisposed in the pixel regions 512. Thus, the grid shielding layer 514separates the light-sensing devices 516 from each other. In someexamples, each light-sensing device 516 includes an image sensorelement, in which the image sensor element includes a photodiode andother elements.

In some examples, a passivation layer 518 is formed on the first surface506 of the semiconductor layer 504 and covering the light-sensingdevices 516, the grid shielding layer 514 and the first surface 506 ofthe semiconductor layer 504 for protecting the light-sensing devices516, the grid shielding layer 514 and the semiconductor layer 504 frombeing damaged. The passivation layer 518 may be formed from siliconoxide, silicon nitride or silicon oxynitride. In some exemplaryexamples, the operation of forming the passivation layer 518 isperformed using a deposition technique, such a CVD technique and aplasma enhanced CVD (PECVD) technique.

As shown in FIG. 5D, in some examples, another substrate 524 is providedand then is bonded to the passivation layer 518. In such examples, thepassivation layer 518 may be formed from silicon dioxide. In addition,the substrate 524 is a semiconductor substrate and may be composed of asingle-crystalline semiconductor material or a compound semiconductormaterial. For example, silicon, germanium or glass may be used as amaterial of the substrate 524. In certain examples, a bonding layer 520is additionally formed on the passivation layer 518 between theoperation of forming the passivation layer 518 and the operation ofbonding the substrate 524. After the bonding layer 520 is formed, thesubstrate 524 is bonded to a surface 522 of the bonding layer 520. Forexample, the bonding layer 520 may be formed from silicon dioxide. Insuch examples, the passivation layer 518 may be formed from siliconoxide, silicon nitride or silicon oxynitride. With the bonding layer520, a bonding effect of the operation of bonding the substrate 524 isenhanced.

As shown in FIG. 5E, after the bonding operation is finished, thestructure composed of the substrate 500, the semiconductor layer 504,the grid shielding layer 514, the light-sensing devices 516, thepassivation layer 518, the bonding layer 520 and the substrate 524 isreversed, and the substrate 500 is removed to expose the second surface508 of the semiconductor layer 504. In some examples, the operation ofremoving the substrate 500 is performed using a thinning technique, suchas a wet etching technique and a CMP technique.

As shown in FIG. 5F, various microstructures 528 are formed on thesecond surface 508 of the semiconductor layer 504. In some examples, theoperation of forming the microstructures 528 is performed using aphotolithography process and an etching process. The photolithographyprocess is performed to define regions where the microstructures 528 areformed, and the etching process is performed on the second surface 508to remove a portion of the semiconductor layer 504 so as to form themicrostructures 528 on the second surface 508 according to thedefinition of the photolithography process. In some exemplary examples,the operation of forming the microstructures 528 is similar to theoperation of forming the microstructures 314 described above. In someexamples, each microstructure 528 is formed with a cross-section in ashape of triangle, trapezoid or arc such as semi-circle or semi-ellipse.The microstructures 528 may be formed periodically or unperiodically. Inaddition, the operation of forming the microstructures 528 may beperformed to form any two adjacent microstructures 528 adjoining to eachother or being separated from each other.

As shown in FIG. 5G, a transparent dielectric layer 530 is formed on thesecond surface 508 of the semiconductor layer 504 and covering themicrostructures 528 to complete a semiconductor device 536. In someexamples, in the operation of forming the transparent dielectric layer530, the transparent dielectric layer 530 is firstly formed to cover themicrostructures 528, and then a planarization operation is performed onthe transparent dielectric layer 530 to planarize a surface 532 of thetransparent dielectric layer 530. Thus, the surface 532 of thetransparent dielectric layer 530 is planar after the planarizationoperation. In some exemplary examples, the operation of forming thetransparent dielectric layer 530 is performed using a thermal oxidationtechnique or a CVD technique. In addition, the planarization operationis performed using a CMP technique. In some examples, the operation offorming the transparent dielectric layer 530 includes forming thetransparent dielectric layer 530 using a material having a refractiveindex which is smaller than a refractive index of the semiconductorlayer 504. For example, the operation of forming the transparentdielectric layer 530 includes forming the transparent dielectric layer530 from silicon dioxide, silicon nitride or silicon oxynitride whilethe operation of the semiconductor layer 504 includes forming thesemiconductor layer 504 from epitaxial silicon.

In some examples, after the operation of forming the transparentdielectric layer 530, a passivation layer 534 may be optionally formedon the surface 532 of the transparent dielectric layer 530 forprotecting the transparent dielectric layer 530 from being damaged. Thepassivation layer 534 may be formed from silicon oxide, silicon nitrideor silicon oxynitride.

Referring to FIG. 6 with FIG. 5A through FIG. 5G, FIG. 6 is a flow chartof a method for manufacturing a semiconductor device in accordance withvarious embodiments. The method begins at operation 600, where asubstrate 500 is provided, and a semiconductor layer 504 is formed on asurface 502 of the substrate 500, as shown in FIG. 5A. The semiconductorlayer 504 may be formed using, for example, a deposition technique or anepitaxial technique. The semiconductor layer 504 has a first surface 506and a second surface 508 opposite to the first surface 506. In someexamples, a thickness of the semiconductor layer 504 ranges from 0.1micrometers to 20 micrometers.

At operation 602, as shown in FIG. 5B, a grid shielding layer 514 isformed in the semiconductor layer 504. In the operation of forming thegrid shielding layer 514, a trench 510 is formed in the semiconductorlayer 504 using, for example, a photolithography process and an etchingprocess. The trench 510 is formed to extend from the first surface 506toward the second surface 508 of the semiconductor layer 504, so as todefine pixel regions 512 in the semiconductor layer 504. The operationof forming the trench 510 includes forming the trench 512 surroundingeach of the pixel regions 512 and separating the pixel regions 512 fromeach other. Then, the grid shielding layer 514 is formed to fill intothe trench 510 by using a deposition technique, such as a CVD technique.The trench 510 surrounds each of the pixel regions 512 and separates thepixel regions 512 from each other, so that the grid shielding layer 514filling the trench 510 extends from the first surface 506 toward thesecond surface 508 and surrounds each of the pixel regions 512 toseparate the pixel regions 512 from each other. In some examples, adepth of the grid shielding layer 514 is greater than two-thirds of thethickness of the semiconductor layer 504. In certain examples, the gridshielding layer 514 penetrates through the semiconductor layer 504, andthe depth of the grid shielding layer 514 is equal to the thickness ofthe semiconductor layer 504. A removal operation may be optionallyperformed to remove an excess portion of the grid shielding layer 514 onthe first surface 506 of the semiconductor layer 504.

In some examples, the grid shielding layer 514 is formed from anelectrically insulating material. In some exemplary examples, the gridshielding layer 514 is formed using a material having a refractive indexwhich is smaller than that of the semiconductor layer 504. For example,the grid shielding layer 514 is formed from silicon dioxide, siliconnitride or silicon oxynitride.

At operation 604, as shown in FIG. 5C, various light-sensing devices 516are formed on the first surface 506 of the semiconductor layer 504 andare respectively disposed in the pixel regions 512. The grid shieldinglayer 514 separates the pixel regions 512, so that the grid shieldinglayer 514 separates the light-sensing devices 516 respectively in thepixel regions 512 from each other. At operation 606, referring to FIG.5C again, a passivation layer 518 is formed on the first surface 506 ofthe semiconductor layer 504 and covering the light-sensing devices 516,the grid shielding layer 514 and the first surface 506 of thesemiconductor layer 504 for protecting.

At operation 608, as shown in FIG. 5D, another substrate 524 is providedand then is bonded to the passivation layer 518. In such examples, thepassivation layer 518 may be formed from silicon dioxide, and thesubstrate 524 may be formed form a semiconductor material, such assilicon, germanium and glass. In certain examples, a bonding layer 520is additionally formed on the passivation layer 518 before the operationof bonding the substrate 524. Then, the substrate 524 is bonded to asurface 522 of the bonding layer 520. For example, the bonding layer 520may be formed from silicon dioxide, and the passivation layer 518 may beformed from silicon oxide, silicon nitride or silicon oxynitride.

At operation 610, as shown in FIG. 5E, the structure composed of thesubstrate 500, the semiconductor layer 504, the grid shielding layer514, the light-sensing devices 516, the passivation layer 518, thebonding layer 520 and the substrate 524 is reversed, and the substrate500 is removed to expose the second surface 506 of the semiconductorlayer 504 using, for example, a thinning technique. In some exemplaryexamples, the operation of removing the substrate 500 is performed usinga wet etching technique and a chemical mechanical polishing technique.

At operation 612, as shown in FIG. 5F, various microstructures 528 areformed on the second surface 508 of the semiconductor layer 504 byusing, for example, a photolithography process and an etching process.The operation of forming the microstructures 528 may be performed toform each microstructure 528 with a cross-section in a shape oftriangle, trapezoid or arc such as semi-circle or semi-ellipse. Themicrostructures 528 may be formed periodically or unperiodically. Inaddition, the operation of forming the microstructures 528 may beperformed to form any two adjacent microstructures 314 adjoining to eachother or being separated from each other.

At operation 614, as shown in FIG. 5G, a transparent dielectric layer530 is formed on the second surface 508 of the semiconductor layer 504,and covers the microstructures 528 by using, for example, a thermaloxidation technique or a chemical vapor deposition technique, so as tocomplete a semiconductor device 536. In some examples, a planarizationoperation may be optionally performed on the transparent dielectriclayer 530 by using, for example, a CMP technique, so as to planarize asurface 532 of the transparent dielectric layer 530. The operation offorming the transparent dielectric layer 530 includes forming thetransparent dielectric layer 530 using a material having a refractiveindex which is smaller than a refractive index of the semiconductorlayer 504. In some exemplary examples, the operation of forming thetransparent dielectric layer 530 includes forming the transparentdielectric layer 530 from silicon dioxide, silicon nitride or siliconoxynitride. Optionally, a passivation layer 534 may be formed to coverthe surface 532 of the transparent dielectric layer 530 for protectingthe transparent dielectric layer 530 from being damaged.

In accordance with an embodiment, the present disclosure discloses asemiconductor device. The semiconductor device includes a substrate, asemiconductor layer, light-sensing devices, a transparent dielectriclayer and a grid shielding layer. The semiconductor layer is overlyingthe substrate and having a first surface and a second surface oppositeto the first surface. The semiconductor layer includes microstructureson the second surface. The light-sensing devices are disposed on thefirst surface. The transparent dielectric layer is disposed on thesecond surface and covers the microstructures. The grid shielding layerextends from the first surface toward the second surface and surroundseach of the light-sensing devices to separate the light-sensing devicesfrom each other, in which a depth of the grid shielding layer is greaterthan two-thirds of a thickness of the semiconductor layer.

In accordance with another embodiment, the present disclosure disclosesa method for manufacturing a semiconductor device. In this method, afirst substrate is provided, and a semiconductor layer is formed on asurface of the first substrate. The semiconductor layer has a firstsurface and a second surface opposite to the first surface.Microstructures are formed on the second surface. A transparentdielectric layer is formed on the second surface and covering themicrostructures. A second substrate is bonded to the transparentdielectric layer. The first substrate is removed to expose the firstsurface. A grid shielding layer is formed to extend from the firstsurface toward the second surface to define the semiconductor layer intopixel regions, in which the grid shielding layer surrounds each of thepixel regions to separate the pixel regions from each other, and a depthof the grid shielding layer is greater than two-thirds of a thickness ofthe semiconductor layer. Light-sensing devices are respectively formedon the first surface in the pixel regions.

In accordance with yet another embodiment, the present disclosurediscloses a method for manufacturing a semiconductor device. In thismethod, a first substrate is provided, and a semiconductor layer isformed on a surface of the first substrate. The semiconductor layer hasa first surface and a second surface opposite to the first surface. Agrid shielding layer is formed to extend from the first surface towardthe second surface, so as to define the semiconductor layer into pixelregions, in which the grid shielding layer surrounds each of the pixelregions to separate the pixel regions from each other, and a depth ofthe grid shielding layer is greater than two-thirds of a thickness ofthe semiconductor layer. Light-sensing devices are respectively formedon the first surface in the pixel regions. A first passivation layer isformed to cover the light-sensing devices and the first surface. Asecond substrate is bonded on the first passivation layer. The firstsubstrate is removed to expose the second surface. Microstructures areformed on the second surface. A transparent dielectric layer is formedon the second surface and covering the microstructures.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method for manufacturing a semiconductordevice, the method comprising: providing a first substrate on which asemiconductor layer is formed on a surface of the first substrate, thesemiconductor layer having a first surface and a second surface oppositeto the first surface; forming a plurality of microstructures on thesecond surface; forming a transparent dielectric layer on the secondsurface and covering the microstructures; bonding a second substrate tothe transparent dielectric layer; removing the first substrate to exposethe first surface; forming a grid shielding layer extending from thefirst surface toward the second surface to define the semiconductorlayer into a plurality of pixel regions, wherein the grid shieldinglayer surrounds each of the pixel regions to separate the pixel regionsfrom each other, and a depth of the grid shielding layer is greater thantwo-thirds of a thickness of the semiconductor layer; and forming aplurality of light-sensing devices respectively on the first surface inthe pixel regions.
 2. The method of claim 1, wherein forming thetransparent dielectric layer comprises: forming the transparentdielectric layer to cover the microstructures; and performing aplanarization operation on the transparent dielectric layer to form thetransparent dielectric layer having a planar surface.
 3. The method ofclaim 1, wherein forming the transparent dielectric layer comprisesforming the transparent dielectric layer using a material having arefractive index which is smaller than a refractive index of thesemiconductor layer.
 4. The method of claim 1, wherein forming thetransparent dielectric layer comprises forming the transparentdielectric layer from silicon dioxide, silicon nitride, or siliconoxynitride, and providing the first substrate comprises forming thesemiconductor layer from epitaxial silicon.
 5. The method of claim 1,wherein forming the grid shielding layer comprises: forming a trenchextending from the first surface toward the second surface to form thepixel regions in the semiconductor layer, wherein forming the trenchcomprises forming the trench surrounding each of the pixel regions toseparate the pixel regions from each other; and forming the gridshielding layer to fill into the trench.
 6. The method of claim 1,wherein forming the grid shielding layer comprises forming the gridshielding layer using a material having a refractive index which issmaller than a refractive index of the semiconductor layer.
 7. Themethod of claim 1, wherein forming the grid shielding layer comprisesforming the grid shielding layer from silicon dioxide, silicon nitride,or silicon oxynitride.
 8. The method of claim 1, wherein thesemiconductor layer is formed to have a thickness ranging fromsubstantially 0.1 micrometers to substantially 20 micrometers.
 9. Themethod of claim 1, wherein each of the microstructures is formed with across-section in a shape of triangle, trapezoid, semi-circle orsemi-ellipse.
 10. The method of claim 1, further comprising forming apassivation layer on the first surface of the semiconductor layer afterforming the light-sensing devices, the passivation layer covering thelight-sensing devices, the grid shielding layer, and the first surfaceof the semiconductor layer.
 11. The method of claim 1, wherein the depthof the grid shielding layer is substantially equal to the thickness ofthe semiconductor layer.
 12. A method for manufacturing a semiconductordevice, the method comprising: providing a first substrate on which asemiconductor layer is formed on a surface of the first substrate, andthe semiconductor layer having a first surface and a second surfaceopposite to the first surface; forming a grid shielding layer extendingfrom the first surface toward the second surface to define thesemiconductor layer into a plurality of pixel regions, wherein the gridshielding layer surrounds each of the pixel regions to separate thepixel regions from each other, and a depth of the grid shielding layeris greater than two-thirds of a thickness of the semiconductor layer;forming a plurality of light-sensing devices respectively on the firstsurface in the pixel regions; forming a first passivation layer to coverthe light-sensing devices, the first surface and the grid shieldinglayer; bonding a second substrate on the first passivation layer;removing the first substrate to expose the second surface; forming aplurality of microstructures on the second surface; and forming atransparent dielectric layer on the second surface and covering themicrostructures.
 13. The method of claim 12, wherein forming the gridshielding layer comprises: forming a trench extending from the firstsurface toward the second surface to form the pixel regions in thesemiconductor layer, wherein forming the trench comprises forming thetrench surrounding each of the pixel regions to separate the pixelregions from each other; and forming the grid shielding layer to fillinto the trench.
 14. The method of claim 12, wherein forming the gridshielding layer comprises forming the grid shielding layer using amaterial having a refractive index which is smaller than a refractiveindex of the semiconductor layer.
 15. The method of claim 12, whereinforming the grid shielding layer comprises forming the grid shieldinglayer from silicon dioxide, silicon nitride, or silicon oxynitride. 16.The method of claim 12, between forming the first passivation layer andbonding the second substrate, the method further comprises forming abonding layer on the first passivation layer, wherein the bonding thesecond substrate comprises providing the second substrate formed fromsilicon and bonding the second substrate to the bonding layer.
 17. Themethod of claim 12, wherein forming the transparent dielectric layercomprises: forming the transparent dielectric layer to cover themicrostructures; and performing a planarization operation on thetransparent dielectric layer to form the transparent dielectric layerhaving a planar surface.
 18. The method of claim 12, after forming thetransparent dielectric layer, the method further comprises forming asecond passivation layer on the transparent dielectric layer.
 19. Themethod of claim 12, wherein forming the transparent dielectric layercomprises forming the transparent dielectric layer using a materialhaving a refractive index which is smaller than a refractive index ofthe semiconductor layer.
 20. The method of claim 12, wherein the depthof the grid shielding layer is substantially equal to the thickness ofthe semiconductor layer.